Sharpener for mechanical pencil leads



April 1, 1941. .w. J. TRbEBER 2,236.979

SHARPENER FOR MECHANICAL PENCILLEADS Filed June 1, 1940,

Infi lg:

I! film ng llllllllllllll/J H Q lNVENT R Patented Apr. 1, 1941 UNHTED STATES PATENT OFFICE SHARPENER FOR MECHANICAL PEN CIL LEADS 16 Claims.

This invention relates in general to devices for forming points on pencils, crayons and the like, and more particularly the invention contemplates a device especially adapted for use in sharpening leads of mechanical pencils.

The problem of forming sharp points on the leads of mechanical pencils is difficult, first, because the leads generally are of small diameter and can be easily broken by cutting or abrasion and by slight lateral strains, and, second, because the leads are held by cases formed of hard material such as metal or composition which must not be defaced by a sharpener and which would quickly dull or break cutters that might contact therewith.

Moreover, the leads generally are held insecurely in their cases which makes it difficult to sharpen a lead with a sharpener that requires frictional contact and relative movement of the lead and sharpener during a sharpening operation.

Furthermore, the leads vary in diameter and the lead-holding tips of the mechanical pencils also vary in diameter and shape or degree of taper.

One object of my invention is to provide a sharpener of the character described that shall embody novel and improved features of construction to overcome the above-mentioned difficulties, and shall enable the sharpening of a mechanical pencil lead rapidly and with ease and certainty,

Another object is to provide a novel and improved cutter for such a sharpener whereby a lead may be sharpened with a minimum of frictional pressure and there shall be a minimum of possibility of lateral breaking strains on the lead during the sharpening operation.

Further objects are to provide a sharpener for the leads of mechanical pencils that shall embody novel and improved features of construction to prevent contact of the case of the pencil with the cutters of the sharpener; to provide such a sharpener that shall be constructed to 4 Figure 1 is a front perspective view of asharp- 1 proximately rectangular in shape.

Figure 2 is a vertical sectional view on the line 2-2 of Figure 1.

Figure 3 is a horizontal sectional view on the line 33 of Figure 2.

Figure 4 is a transverse vertical sectional view on the line 4-4 of Figure 2.

Figure 5 is a detached rear perspective view of the cutter blocks and the supporting plate.

Figure 6 is a view similar to Figure 2 showing a modified form of the invention.

Figure '7 is an enlarged detached perspective view of one cutter block.

Figure 8 is a view similar to Figure 2 showing a further modification of the invention.

Figure 9 is a horizontal sectional view on the line 99 of Figure 8, and

Figure 10 is a detached perspective view of the supporting plate for the cutter blocks shown in Figures 8 and 9.

Specifically describing the illustrated embodiment of the invention, the sharpener includes twocutter blocks A preferably formed of steel and each having two angularly related sides I and 2 meeting in a corner 3 and having a notch 4 V-shaped in cross-section in said corner whose sides 5 and 6 are disposed in angularly related planes, meet each other throughout their lengths and intersect the respective sides I and 2 of the block to form edges 1 which converge toward each other in a common plane and meet at said corner. Conveniently, the blocks may be ap- Two blocks are mounted in juxtaposed relation to each other with the corners 3 in close proximity and with at least one edge 1 of each notch disposed approximately in a common plane with one edge of the other notch and "constituting a cutter so that said notches may receive a pencil lead be tween them in contact with said cutters.

As shown, the edges I extend inwardly from one surface 8 of the corresponding block, and these surfaces serve for connecting the blocks to the holding means which is shown in the form of a plate 8 secured to said surfaces and having an opening 9 in alinement with the space between notches 4 to guide a pencil lead into contact with the edges 1. The plate may be secured the diameter of the end of the lead holding tip C of a mechanical pencil D so that the lead freely may pass through the opening to contact with the cutters, but the end of the pencil tip will abut the plate around the opening so that the tip is prevented. from contacting with the cutters.

The angle of convergence of the cutting edges 7 preferably is such as to form the desired taper on the sharpened end of the pencil lead.

In operation of the invention sofar described, when it is desired to sharpen the lead B of a pencil, the lead is projected from the tip of the pencil the desired distance and inserted in the open ing 9 into contact with the cutting edges I. The plate and blocks are then rotated relatively to the pencil lead, whereupon the cutting edges 1 will shave the lead to produce a point thereon. Preferably all of the edges 7 are adapted to serve as cutting edges, the two edges of the blocks A in one plane serving to shave the lead upon relative rotation of the sharpener and lead in one direction, and the other two edges 7 serving to shave the lead upon relative rotation of the sharpener and lead in the opposite direction. It will be noted that the side 5 or 6 of each notch opposite the edge I that is serving as a cutter at any given time, forms a rest or support for the lead so that the lead is accurately held in contact with the cutting edges and with a minimum possibility of lateral breaking strains on the point of the lead.

Conveniently, the plate and blocks are enclosed in a casing which in Figures 1 to 4 inclusive, comp-rises a box-like structure E formed of suitable material, for example a synthetic composition. The plate 8 abuts the wall of the casing E opposite the open side thereof and has anopening H in register with the opening 9 and of sufficient diameter to receive the end of the lead holding tip C of the pencil. The plate and blocks are held in the casing by inserts l2 that may be formed of the same material as the casing and secured thereto in any suitable manner in abutting relation to the blocks A, as shown in Figure 3. Conveniently, the inserts may be made of the same plastic material as the casing and secured to the casing by a known commercial adhesive;

In the form of the invention shown in Figure 6, the rivets Ii] maypass through the blocks A, the plate 8 and the wall of the casing E, so as to serve both to secure the blocks: to the plate and to secure the blocks and plate to the casing.

A further modification of the invention is shown in Figures 8' to 10 inclusive where the blocks are of the same structure as heretofore described but are secured on a difierent type of supporting plate I3. This plate is formed of sheet metal and has upturned flanges M at its edges to snugly fit within the casing F in abutting relation to a shoulder 2i. The plate also has upstanding lugs l5 stamped therefrom so that each block may be secured against lateral movement on the plate by contact of one flange 14 with one side of the block and contact of each of the other three sides of the block with one of the lugs l5. For holding the plates and blocks in the casing, the edges of the casing may be turned inwardly to form ears l6 overlying the respective blocks A as shown in Figures 8 and 9, or other suitable means may be utilized for the purpose.

In some instances it may be desired to provide means for accurately guiding and holding the pencil lead against lateralmovement while it is in contactwith the cutters, and forthis purpose, I may provide a guide socket IT in alinement with the opening 9 in the supporting plate to be engaged by the sides of the lead holding tip.

7 The lead holding tips of mechanical pencils vary in shapes and dimensions and accordingly 5 I make the walls of the socket ll resilient or yieldable so that the socket may accommodate itself to difierent lead holding tips. As shown in Figures 8 and 9, the socket is composed of a plurality of complemental segments I8 which are fitted into an opening IS in a block of resilient material such as rubber, which is arranged in the casing F between its front wall and the plate I3. Instead of rubber, a spring might be utilized; and in some instances the socket may be formed by the walls of the open ing in the resilient block 20, or a solid block with a tapered socket could be used, so as to eliminate the necessity for the socket segments I8. Also, the socket might be inherently resilent and secured directly, to the plate I3 to eliminate the rubber block 20.

In use, the lead holding tip is pressed into the socket to insert the lead through the opening '9, and the Walls of the socket will yield to accomagainst such lateral movements during the sharpening operation as might exert lateral breaking strains on the lead while it is in contact with the cutters.

Other modifications and changes in the structure of the invention will occur to those skilled in the art as within the spirit'and scope of the invention.

Having thus described my invention, what I claim is:

1. A device of the character described comprising a pair of juxtaposed blocks and means for holding them, each block having a notch in its .surface in opposed relation to the notch in the other block so that said notches may receive and guide a lead between them, at least one edge-of one of said notches constituting a cutter.

2. The device set forth in claim 1 wherein'the edges'of each notch converge toward each other.

3. A sharpener for the leads of mechanical pencils comprising a cutter and a holder therefor having an opening to permit insertion of a lead therethrough into contact with said cutter,

and a guide socket in alinement with said opening and having expansible walls to accommodate lead holding tips of different shapes and dimensions.

4. A sharpener for the leads of mechanical Mpencils comprising a cutter and a holder therefor having an opening to permit insertion of a lead therethrough into contact with said cutter,

a guide socket in alinement with said opening and comprising a plurality of complemental segments, and resilient means surrounding said 0' socket to permit yielding relative movement of said segments to accommodate lead holding tips of different shapesand dimensions.

5. The device set'forth in claim lwherein said means for holding said blocks comprises a plateon which said blocks are rigidly mounted, said.

modate the tip and thereafter hold the pencil ing edge, and with the addition of a casing enclosing said plate and said blocks.

'7. A device of the character described comprising a pair of juxtaposed blocks and means for holding them, each block having a notch in its surface in opposed relation to the notch in the other block so that said notches may receive and guide a lead between them, the edges of each notch converging toward each other in approximately a common plane and each edge to contact with a lead inserted into the space between the notches and each edge of each notch constituting a cutter upon relative rotation of said device and said lead in opposite directions respectively.

8. A sharpener for the leads of mechanical pencils comprising a pair of blocks, each having two angularly related sides meeting in a corner and a notch V-shaped in cross-section in said corner and whose sides are disposed in angularly related planes and intersect the respective said sides of the block to form edges which converge toward each other and meet at said corner, and means for holding said blocks with said corners in close proximity to each other and with at least one said edge of each notch disposed approximately in a common plane with one edge of the other notch and constituting a cutter so that said notches may receive a pencil lead between them in contact with said cutter.

9. A cutter for a sharpener for mechanical pencil leads comprising a block having two angularly related sides meeting in a corner and a notch V-shaped in cross-section in said corner and whose sides are disposed in angularly related planes and intersect the respective said sides of the block to form edges which converge toward each other and meet at said corner.

10. A device of the character described comprising a pair of juxtaposed blocks and means for holding them, each block having a cutting edge extending inwardly from one surface thereof and converging toward the corresponding edge of the other block approximately in a common plane to receive a lead between them.

11. The device set forth in claim 10 wherein said means for holding the blocks is a plate secured to said surfaces of said blocks and having an opening in alinement with the space between said edges to guide a pencil lead into contact with said edges.

12. A device of the character described comprising a pair of juxtaposed blocks and means for holding them, each block having a notch in its surface in opposed relation to the notch in the other block so that said notches may receive and guide a lead between them, the edges of each notch converging toward each other in approximately a common plane and each side of each notch to contact with a lead inserted into the space between the notches and at least one of said edges constituting a cutter.

13. The device set forth in claim 1 wherein each notch is V-shaped in cross-section with its edges converging toward each other in a common plane.

14. A device of the character described comprising a pair of juxtaposed blocks and means for holding them, at least one block having a notch in its surface one edge of which is a cutter and the other block having a surface in opposed relation to said notch, whereby a pencil lead can be inserted between the sides of said notch and said surface and guided by the sides of said notch and said surface into contact with said cutter.

15. A device of the character described comprising a block having a notch in its surface whose sides meet throughout their lengths and are disposed in angularly related planes, the edges of the notch at the juncture of said sides with the surface of the block converging toward each other, at least one of said edges constituting a cutter.

16. A device of the character described comprising a block having a notch that is V-shaped in cross-section and whose sides meet throughout their lengths, the edges of the notch at the juncture of said sides with the surface of the block converging toward each other in a common plane and at least one of said edges constituting a cutter.

WILLIAM J. TROEBER. 

